Contributors: 51
| Author |
Tokens |
Token Proportion |
Commits |
Commit Proportion |
| Mandeep Singh Baines |
281 |
17.45% |
7 |
7.69% |
| Ingo Molnar |
184 |
11.43% |
11 |
12.09% |
| nixiaoming |
158 |
9.81% |
1 |
1.10% |
| Masami Hiramatsu |
148 |
9.19% |
1 |
1.10% |
| Lance Yang |
128 |
7.95% |
3 |
3.30% |
| Tetsuo Handa |
103 |
6.40% |
6 |
6.59% |
| Vitaly Kuznetsov |
76 |
4.72% |
1 |
1.10% |
| Oleg Nesterov |
67 |
4.16% |
3 |
3.30% |
| Dmitriy Vyukov |
59 |
3.66% |
1 |
1.10% |
| Christoph Hellwig |
46 |
2.86% |
1 |
1.10% |
| Eric Dumazet |
45 |
2.80% |
1 |
1.10% |
| Peter Zijlstra |
40 |
2.48% |
6 |
6.59% |
| Linus Torvalds (pre-git) |
39 |
2.42% |
5 |
5.49% |
| Guilherme G. Piccoli |
37 |
2.30% |
1 |
1.10% |
| Marcelo Tosatti |
35 |
2.17% |
1 |
1.10% |
| Art Haas |
30 |
1.86% |
1 |
1.10% |
| Oxana Kharitonova |
13 |
0.81% |
1 |
1.10% |
| Liu Hua |
11 |
0.68% |
1 |
1.10% |
| fuyuanli |
10 |
0.62% |
1 |
1.10% |
| Pavel Machek |
9 |
0.56% |
2 |
2.20% |
| Linus Torvalds |
8 |
0.50% |
2 |
2.20% |
| Chuansheng Liu |
8 |
0.50% |
1 |
1.10% |
| Aaron Tomlin |
7 |
0.43% |
2 |
2.20% |
| Frédéric Weisbecker |
5 |
0.31% |
1 |
1.10% |
| Kent Overstreet |
5 |
0.31% |
1 |
1.10% |
| Tom Rix |
4 |
0.25% |
1 |
1.10% |
| Hideaki Yoshifuji / 吉藤英明 |
4 |
0.25% |
1 |
1.10% |
| Rasmus Villemoes |
4 |
0.25% |
1 |
1.10% |
| Glauber de Oliveira Costa |
4 |
0.25% |
1 |
1.10% |
| Andy Shevchenko |
3 |
0.19% |
1 |
1.10% |
| Andrew Morton |
3 |
0.19% |
1 |
1.10% |
| Joel Granados |
3 |
0.19% |
3 |
3.30% |
| Valdis Kletnieks |
3 |
0.19% |
1 |
1.10% |
| Andi Kleen |
3 |
0.19% |
1 |
1.10% |
| John Siddle |
3 |
0.19% |
1 |
1.10% |
| Vegard Nossum |
3 |
0.19% |
1 |
1.10% |
| Paul Gortmaker |
2 |
0.12% |
2 |
2.20% |
| Vineet Gupta |
2 |
0.12% |
1 |
1.10% |
| Matteo Croce |
2 |
0.12% |
1 |
1.10% |
| Yongliang Gao |
2 |
0.12% |
1 |
1.10% |
| Alexei Starovoitov |
2 |
0.12% |
1 |
1.10% |
| Måns Rullgård |
2 |
0.12% |
1 |
1.10% |
| Eric W. Biedermann |
1 |
0.06% |
1 |
1.10% |
| Sasha Levin |
1 |
0.06% |
1 |
1.10% |
| Li Zefan |
1 |
0.06% |
1 |
1.10% |
| Alan Stern |
1 |
0.06% |
1 |
1.10% |
| Jeff Mahoney |
1 |
0.06% |
1 |
1.10% |
| Patrick Mochel |
1 |
0.06% |
1 |
1.10% |
| Anton Blanchard |
1 |
0.06% |
1 |
1.10% |
| John Kacur |
1 |
0.06% |
1 |
1.10% |
| Thomas Gleixner |
1 |
0.06% |
1 |
1.10% |
| Total |
1610 |
|
91 |
|
// SPDX-License-Identifier: GPL-2.0-only
/*
* Detect Hung Task
*
* kernel/hung_task.c - kernel thread for detecting tasks stuck in D state
*
*/
#include <linux/mm.h>
#include <linux/cpu.h>
#include <linux/nmi.h>
#include <linux/init.h>
#include <linux/delay.h>
#include <linux/freezer.h>
#include <linux/kthread.h>
#include <linux/lockdep.h>
#include <linux/export.h>
#include <linux/panic_notifier.h>
#include <linux/sysctl.h>
#include <linux/suspend.h>
#include <linux/utsname.h>
#include <linux/sched/signal.h>
#include <linux/sched/debug.h>
#include <linux/sched/sysctl.h>
#include <linux/hung_task.h>
#include <trace/events/sched.h>
/*
* The number of tasks checked:
*/
static int __read_mostly sysctl_hung_task_check_count = PID_MAX_LIMIT;
/*
* Total number of tasks detected as hung since boot:
*/
static unsigned long __read_mostly sysctl_hung_task_detect_count;
/*
* Limit number of tasks checked in a batch.
*
* This value controls the preemptibility of khungtaskd since preemption
* is disabled during the critical section. It also controls the size of
* the RCU grace period. So it needs to be upper-bound.
*/
#define HUNG_TASK_LOCK_BREAK (HZ / 10)
/*
* Zero means infinite timeout - no checking done:
*/
unsigned long __read_mostly sysctl_hung_task_timeout_secs = CONFIG_DEFAULT_HUNG_TASK_TIMEOUT;
EXPORT_SYMBOL_GPL(sysctl_hung_task_timeout_secs);
/*
* Zero (default value) means use sysctl_hung_task_timeout_secs:
*/
static unsigned long __read_mostly sysctl_hung_task_check_interval_secs;
static int __read_mostly sysctl_hung_task_warnings = 10;
static int __read_mostly did_panic;
static bool hung_task_show_lock;
static bool hung_task_call_panic;
static bool hung_task_show_all_bt;
static struct task_struct *watchdog_task;
#ifdef CONFIG_SMP
/*
* Should we dump all CPUs backtraces in a hung task event?
* Defaults to 0, can be changed via sysctl.
*/
static unsigned int __read_mostly sysctl_hung_task_all_cpu_backtrace;
#else
#define sysctl_hung_task_all_cpu_backtrace 0
#endif /* CONFIG_SMP */
/*
* Should we panic (and reboot, if panic_timeout= is set) when a
* hung task is detected:
*/
static unsigned int __read_mostly sysctl_hung_task_panic =
IS_ENABLED(CONFIG_BOOTPARAM_HUNG_TASK_PANIC);
static int
hung_task_panic(struct notifier_block *this, unsigned long event, void *ptr)
{
did_panic = 1;
return NOTIFY_DONE;
}
static struct notifier_block panic_block = {
.notifier_call = hung_task_panic,
};
#ifdef CONFIG_DETECT_HUNG_TASK_BLOCKER
static void debug_show_blocker(struct task_struct *task)
{
struct task_struct *g, *t;
unsigned long owner, blocker, blocker_type;
RCU_LOCKDEP_WARN(!rcu_read_lock_held(), "No rcu lock held");
blocker = READ_ONCE(task->blocker);
if (!blocker)
return;
blocker_type = hung_task_get_blocker_type(blocker);
switch (blocker_type) {
case BLOCKER_TYPE_MUTEX:
owner = mutex_get_owner(
(struct mutex *)hung_task_blocker_to_lock(blocker));
break;
case BLOCKER_TYPE_SEM:
owner = sem_last_holder(
(struct semaphore *)hung_task_blocker_to_lock(blocker));
break;
default:
WARN_ON_ONCE(1);
return;
}
if (unlikely(!owner)) {
switch (blocker_type) {
case BLOCKER_TYPE_MUTEX:
pr_err("INFO: task %s:%d is blocked on a mutex, but the owner is not found.\n",
task->comm, task->pid);
break;
case BLOCKER_TYPE_SEM:
pr_err("INFO: task %s:%d is blocked on a semaphore, but the last holder is not found.\n",
task->comm, task->pid);
break;
}
return;
}
/* Ensure the owner information is correct. */
for_each_process_thread(g, t) {
if ((unsigned long)t != owner)
continue;
switch (blocker_type) {
case BLOCKER_TYPE_MUTEX:
pr_err("INFO: task %s:%d is blocked on a mutex likely owned by task %s:%d.\n",
task->comm, task->pid, t->comm, t->pid);
break;
case BLOCKER_TYPE_SEM:
pr_err("INFO: task %s:%d blocked on a semaphore likely last held by task %s:%d\n",
task->comm, task->pid, t->comm, t->pid);
break;
}
sched_show_task(t);
return;
}
}
#else
static inline void debug_show_blocker(struct task_struct *task)
{
}
#endif
static void check_hung_task(struct task_struct *t, unsigned long timeout)
{
unsigned long switch_count = t->nvcsw + t->nivcsw;
/*
* Ensure the task is not frozen.
* Also, skip vfork and any other user process that freezer should skip.
*/
if (unlikely(READ_ONCE(t->__state) & TASK_FROZEN))
return;
/*
* When a freshly created task is scheduled once, changes its state to
* TASK_UNINTERRUPTIBLE without having ever been switched out once, it
* musn't be checked.
*/
if (unlikely(!switch_count))
return;
if (switch_count != t->last_switch_count) {
t->last_switch_count = switch_count;
t->last_switch_time = jiffies;
return;
}
if (time_is_after_jiffies(t->last_switch_time + timeout * HZ))
return;
/*
* This counter tracks the total number of tasks detected as hung
* since boot.
*/
sysctl_hung_task_detect_count++;
trace_sched_process_hang(t);
if (sysctl_hung_task_panic) {
console_verbose();
hung_task_show_lock = true;
hung_task_call_panic = true;
}
/*
* Ok, the task did not get scheduled for more than 2 minutes,
* complain:
*/
if (sysctl_hung_task_warnings || hung_task_call_panic) {
if (sysctl_hung_task_warnings > 0)
sysctl_hung_task_warnings--;
pr_err("INFO: task %s:%d blocked for more than %ld seconds.\n",
t->comm, t->pid, (jiffies - t->last_switch_time) / HZ);
pr_err(" %s %s %.*s\n",
print_tainted(), init_utsname()->release,
(int)strcspn(init_utsname()->version, " "),
init_utsname()->version);
if (t->flags & PF_POSTCOREDUMP)
pr_err(" Blocked by coredump.\n");
pr_err("\"echo 0 > /proc/sys/kernel/hung_task_timeout_secs\""
" disables this message.\n");
sched_show_task(t);
debug_show_blocker(t);
hung_task_show_lock = true;
if (sysctl_hung_task_all_cpu_backtrace)
hung_task_show_all_bt = true;
if (!sysctl_hung_task_warnings)
pr_info("Future hung task reports are suppressed, see sysctl kernel.hung_task_warnings\n");
}
touch_nmi_watchdog();
}
/*
* To avoid extending the RCU grace period for an unbounded amount of time,
* periodically exit the critical section and enter a new one.
*
* For preemptible RCU it is sufficient to call rcu_read_unlock in order
* to exit the grace period. For classic RCU, a reschedule is required.
*/
static bool rcu_lock_break(struct task_struct *g, struct task_struct *t)
{
bool can_cont;
get_task_struct(g);
get_task_struct(t);
rcu_read_unlock();
cond_resched();
rcu_read_lock();
can_cont = pid_alive(g) && pid_alive(t);
put_task_struct(t);
put_task_struct(g);
return can_cont;
}
/*
* Check whether a TASK_UNINTERRUPTIBLE does not get woken up for
* a really long time (120 seconds). If that happens, print out
* a warning.
*/
static void check_hung_uninterruptible_tasks(unsigned long timeout)
{
int max_count = sysctl_hung_task_check_count;
unsigned long last_break = jiffies;
struct task_struct *g, *t;
/*
* If the system crashed already then all bets are off,
* do not report extra hung tasks:
*/
if (test_taint(TAINT_DIE) || did_panic)
return;
hung_task_show_lock = false;
rcu_read_lock();
for_each_process_thread(g, t) {
unsigned int state;
if (!max_count--)
goto unlock;
if (time_after(jiffies, last_break + HUNG_TASK_LOCK_BREAK)) {
if (!rcu_lock_break(g, t))
goto unlock;
last_break = jiffies;
}
/*
* skip the TASK_KILLABLE tasks -- these can be killed
* skip the TASK_IDLE tasks -- those are genuinely idle
*/
state = READ_ONCE(t->__state);
if ((state & TASK_UNINTERRUPTIBLE) &&
!(state & TASK_WAKEKILL) &&
!(state & TASK_NOLOAD))
check_hung_task(t, timeout);
}
unlock:
rcu_read_unlock();
if (hung_task_show_lock)
debug_show_all_locks();
if (hung_task_show_all_bt) {
hung_task_show_all_bt = false;
trigger_all_cpu_backtrace();
}
if (hung_task_call_panic)
panic("hung_task: blocked tasks");
}
static long hung_timeout_jiffies(unsigned long last_checked,
unsigned long timeout)
{
/* timeout of 0 will disable the watchdog */
return timeout ? last_checked - jiffies + timeout * HZ :
MAX_SCHEDULE_TIMEOUT;
}
#ifdef CONFIG_SYSCTL
/*
* Process updating of timeout sysctl
*/
static int proc_dohung_task_timeout_secs(const struct ctl_table *table, int write,
void *buffer,
size_t *lenp, loff_t *ppos)
{
int ret;
ret = proc_doulongvec_minmax(table, write, buffer, lenp, ppos);
if (ret || !write)
goto out;
wake_up_process(watchdog_task);
out:
return ret;
}
/*
* This is needed for proc_doulongvec_minmax of sysctl_hung_task_timeout_secs
* and hung_task_check_interval_secs
*/
static const unsigned long hung_task_timeout_max = (LONG_MAX / HZ);
static const struct ctl_table hung_task_sysctls[] = {
#ifdef CONFIG_SMP
{
.procname = "hung_task_all_cpu_backtrace",
.data = &sysctl_hung_task_all_cpu_backtrace,
.maxlen = sizeof(int),
.mode = 0644,
.proc_handler = proc_dointvec_minmax,
.extra1 = SYSCTL_ZERO,
.extra2 = SYSCTL_ONE,
},
#endif /* CONFIG_SMP */
{
.procname = "hung_task_panic",
.data = &sysctl_hung_task_panic,
.maxlen = sizeof(int),
.mode = 0644,
.proc_handler = proc_dointvec_minmax,
.extra1 = SYSCTL_ZERO,
.extra2 = SYSCTL_ONE,
},
{
.procname = "hung_task_check_count",
.data = &sysctl_hung_task_check_count,
.maxlen = sizeof(int),
.mode = 0644,
.proc_handler = proc_dointvec_minmax,
.extra1 = SYSCTL_ZERO,
},
{
.procname = "hung_task_timeout_secs",
.data = &sysctl_hung_task_timeout_secs,
.maxlen = sizeof(unsigned long),
.mode = 0644,
.proc_handler = proc_dohung_task_timeout_secs,
.extra2 = (void *)&hung_task_timeout_max,
},
{
.procname = "hung_task_check_interval_secs",
.data = &sysctl_hung_task_check_interval_secs,
.maxlen = sizeof(unsigned long),
.mode = 0644,
.proc_handler = proc_dohung_task_timeout_secs,
.extra2 = (void *)&hung_task_timeout_max,
},
{
.procname = "hung_task_warnings",
.data = &sysctl_hung_task_warnings,
.maxlen = sizeof(int),
.mode = 0644,
.proc_handler = proc_dointvec_minmax,
.extra1 = SYSCTL_NEG_ONE,
},
{
.procname = "hung_task_detect_count",
.data = &sysctl_hung_task_detect_count,
.maxlen = sizeof(unsigned long),
.mode = 0444,
.proc_handler = proc_doulongvec_minmax,
},
};
static void __init hung_task_sysctl_init(void)
{
register_sysctl_init("kernel", hung_task_sysctls);
}
#else
#define hung_task_sysctl_init() do { } while (0)
#endif /* CONFIG_SYSCTL */
static atomic_t reset_hung_task = ATOMIC_INIT(0);
void reset_hung_task_detector(void)
{
atomic_set(&reset_hung_task, 1);
}
EXPORT_SYMBOL_GPL(reset_hung_task_detector);
static bool hung_detector_suspended;
static int hungtask_pm_notify(struct notifier_block *self,
unsigned long action, void *hcpu)
{
switch (action) {
case PM_SUSPEND_PREPARE:
case PM_HIBERNATION_PREPARE:
case PM_RESTORE_PREPARE:
hung_detector_suspended = true;
break;
case PM_POST_SUSPEND:
case PM_POST_HIBERNATION:
case PM_POST_RESTORE:
hung_detector_suspended = false;
break;
default:
break;
}
return NOTIFY_OK;
}
/*
* kthread which checks for tasks stuck in D state
*/
static int watchdog(void *dummy)
{
unsigned long hung_last_checked = jiffies;
set_user_nice(current, 0);
for ( ; ; ) {
unsigned long timeout = sysctl_hung_task_timeout_secs;
unsigned long interval = sysctl_hung_task_check_interval_secs;
long t;
if (interval == 0)
interval = timeout;
interval = min_t(unsigned long, interval, timeout);
t = hung_timeout_jiffies(hung_last_checked, interval);
if (t <= 0) {
if (!atomic_xchg(&reset_hung_task, 0) &&
!hung_detector_suspended)
check_hung_uninterruptible_tasks(timeout);
hung_last_checked = jiffies;
continue;
}
schedule_timeout_interruptible(t);
}
return 0;
}
static int __init hung_task_init(void)
{
atomic_notifier_chain_register(&panic_notifier_list, &panic_block);
/* Disable hung task detector on suspend */
pm_notifier(hungtask_pm_notify, 0);
watchdog_task = kthread_run(watchdog, NULL, "khungtaskd");
hung_task_sysctl_init();
return 0;
}
subsys_initcall(hung_task_init);